This invention refers to an abrasive tool, such as a disc, strip and the like, for a sanding and polishing machine of the type comprising an abrasive-containing layer and a fabric backing layer adapted to be fastened to a plate on the machine.
It is known that sanding and polishing operations are carried out by machines that use readily detachable and replaceable abrasive discs, abrasive strips, or similar tools, releasably fastened to suitable plates, which move in a generally orbital or reciprocating fashion. In this specification, the term "tool" is used to describe all forms of releasably attached discs, belts or strips and the like.
Such sanding and polishing operations conventionally use fine grits with grit sizes of 80 and smaller and it is the context of such products that this invention finds its greatest utility.
Current sanding and polishing techniques substantially meet the requirements of the industrial sector, for instance, in auto-body assembly lines, as well as the crafts sector such as in auto-body shops. There are, however, widespread complaints about the disadvantage of uneven wear on the abrasive coating.
This results in an inefficient use of the tool, which is discarded before it is completely used up, and poor sanding and polishing performance, probably owing to the fact that the abrasive tends to get stuck in the worn-out area.
In some cases attempts have been made to interpose a polymeric layer between an abrasive sheet and an attachment means comprising a pressure sensitive adhesive (PSA) layer. Such devices have not proved totally satisfactory because of the inherent problems associated with PSA materials such as stringiness, deposition on the plate to which the tool is adhered in use, performance variation with temperature and humidity and so on. In addition, if the PSA is applied directly to the polymeric layer, or to a paper layer attached to the polymeric layer, any plasiticizer present therein can migrate through the paper and deteriorate the PSA very seriously. The present invention permits a much more versatile approach to the use of detachable abrasive tools that at the same time gives distinct additional performance improvements.
The purpose of this invention is to provide an abrasive tool of the type specified which overcomes the disadvantages mentioned above.